This invention relates generally to a cutting apparatus and more particularly to apparatus for cutting a strip-like or wire-like electrode that is removed from a spark erosion machine or electroerosion machine.
The electroerosion machine includes a mechanism which conveys the electrode and an electrode cutting mechanism which is comprised of rotary cutting elements and a counter-tool. The rotary cutting elements and a ring holding the cutting elements are electrically insulated with respect to the drive shaft of the machine and the counter-tool cutting surface is electrically insulated with respect to its mounting support.
Wire cutting means are known from Japanese Pat. Nos. 57-61422, 57-61423 and 58-109226, from Swiss Pat. No. 634 497 and from the unpublished German patent application No. P 35 11 930 of the present Applicant. In all the wire cutting means known from the prior art there is a common problem of the cutting elements, such as blades, very rapidly becoming worn or blunt. When this happens, the electrode is no longer cut off correctly and an accumulation occurs in the machine.
In order to solve this problem, it is suggested in Swiss Pat. No. 634 497 to construct the cutting tool and the counter-tool in a special way and, specifically, as a polygonal bit which cooperates with an anvil, so that the electrode is notched instead of being cut. However, cutting tools made in accordance with the teaching of the Swiss patent became worn to an extent that was not acceptable for continuous automatic operation.
It would appear obvious to manufacture the cutting tool or blades from a wear-resistant, electrically non-conductive material such as a ceramic material. However, this class of material is very difficult to work and, as a result, the blades become very expensive.